I am just back from Makadi Bay in Egypt (5 hr flight to Hurghada then half an hour transfer). Stayed at the Fort Arabesque resort, which has a lovely beach and it's own house reef which is accessible from the beach.

The snorkelling was wonderful, a huge array of tropical marines. They also have their own jetty with a good company operating diving/boat trips at reasonable prices. Lots of boat trips and those submarine boat trips out to deeper reefs, and day trips to small Red Sea islands for more snorkelling.

We have snorkelled in the Caribbean but did not see the range of fish we had here. We bought a large chart and spent the evenings ticking off which fish we'd seen that day.

Not a trip for the summer hols though, too hot I should imagine. But with that flight time, and no jetlag it's workable for a half term.

I wouldn't go to Australia for snorkelling. Of all the places we've been to, our son spent less time in the water there because of the 'stingers'. Plus the trips out to the Barrier Reef will require great confidence as he'll be out in the open sea. Mind you, the Aquarium in Sydney is brilliant.

The best place I've been to for snorkelling is Marsa Alam in Egypt. Snorkelling is great (some will be off a pontoon) but there is a beach where you can snorkel with turtles and still be able to stand up (Marsa Abarak I think). Our five year old did that and snorkelled with lion fish. Saw sea snakes, stingrays etc just from looking from the pontoon. Plus there's a great submarine style boat trip you can take - great for kids.

Have you thought about going to a diving resort/centre. They usually do good snorkelling. She's too young for PADI scuba for adults, but there is the Bubblemaker which introduces children to scuba. Some aquariums allow you to dive in a shallow tank with fish on this course.

Dh and I are both open-water divers and love it. We can't afford to travel too far (though we learned in the Carribean and that was awesome). This summer we're going to Italy and planning a diving drip on the Amalfi Coast.

Our kids had their best snorkelling experience in the Dominican Republic, on the north coast, with the astounding Northern Coast Diving in Sosua. Highly recommended - pedro, their children's snorkel guide, was an utter star!

I second skygirls in recommending the Maldives. It is certainly not just for couples, we have been nine times to various islands, and three of those trips were with grand children of a similar age to yours. Prices vary hugely, and we have usually headed for the cheaper end. The vital thing, as Sky says, is to pick some where with a house reef close to shore and therefore easily accessible at any time. Some resorts require a boat trip to the reef, avoid these. Have a look at Biyadhoo definitely budget end, we think it is like a posh french camp site, but great, friendly atmosphere and one of the best reefs in the Maldives. Also Reethi Beach is brilliant, a bit more expensive, but worth it. Seriously consider going all-inclusive, otherwise you will have to pay for drinking water and your son will get through huge amounts of expensive juice. Finally look at the Maldives Forum on Trip Advisor, there are plenty of very friendly regulars there who will be delighted to help you choose, and one of the things they will tell you is to start saving immediately for your next trip, as you will inevitably succumb to the dread disease of Maldivitis, only alleviated by another trip.

If you're going to Malaysia anyway, go here. It's awesome. We saw turtles, rays, countless starfish and fish just walking from the room to the breakfast area. You don't need to dive to see the fish, but the diving is meant to be spectacular. A truly amazing experience.

Conrad Rangali resort in the Maldives. We took dds there last Easter and had such an amazing time that we went back for Xmas (we live 4 hours from there so not really long haul for us). Dd2 is 8 and did a bubble maker course, but dd2 who is 4 saw plenty of fish snorkeling. It's like swimming in an aquarium and there are even baby sharks swimming right up to the shore. W also did a boat trip and snorkled with whale sharks. It is amazing! Another plus point is that the kids club is fantastic with loads of pirate type activities, hermit crab races etc and as its a small island, our kids had the run of the plac with other kids during happy hour before dinner. The staff were fantastic, cannot rate it highly enough (it's a 2 island resort with both islands linked by a 500m bridge so there are couples and if you want a quiet holiday, you don't stay on the family island where most of the activities are....

Call the reservations office and negotiate on price, we paid considerably less than the rack rate after several chats

Florida keys islamorada. fly into Miami 1.5 hours drive and you are on the keys. right next to John Pennekamp national park the largest underwater national park in the USA. snorkelling 5 miles out and you could almost stand up. never done anything like it. DS was 9 this year when we went. perfect for his age group. glass bottom boat trips the lot. pm for more details.

Some hotels in Sharm have reefs right on their private beaches so you can snorkel all day. We stayed in a Sofitel (Coralia I think) which had its own reef and just through snorkelling I saw turtles, octopus, billions of fish.

Cozumel, a small island off the Yucatan peninsula of Mexico, has fab diving and is a lovely place to holiday. I went aged 11 and snorkelling there was one of my most vivid childhood memories.

Oh and not all islands in the Maldives are coupley. There are family islands too and lots have kids clubs. Lots of islands to cater for different groups. Check out your travel agent for brochures (Kuoni is quite good), or google Maldives to research your most suitable island.

I think the Maldives would be an excellent choice, if a bit expensive and a 10hour flight to boot.

Find an island with a house reef and he can snorkel to his hearts content and see everything from eagle rays to nurse sharks from just a few metres from the beach.

We've been to a few islands but two stand out for the reefs/lagoons. The first one is Olhuveli. A smallish island 40 mins by speedboat from the airport in Male. The house reef is excellent here but there's not much else to do. The second one Soneva Gili, is more luxurious and dear but the water bungalows are fab. the living room is open air and leads to your private sun deck with steps down into the lagoon where you can see baby reef sharks, nesting trigger fish and a whole community around your jetty. If you head to the main part of the island, there is a swimming pool and near the dive shop there is a deeper lagoon for proper snorkelling where you have to surface dive down to see squid, large fish, turtles and the occasional ray.

Also, if DC is 8 he can do a bubble maker scuba course if he's really into the underwater world. Then you are not limited to where you can go.

Thailand is also good and a cheaper alternative to the Maldives. More to do there, but you'd have to take a boat trip to get to the great snorkelling areas-not good if you get seasick. Flight time here is same as Malaysia.

You could also try the Cayman Islands and the famous stingray city, but I don't know much about the islands.